Just how the wires really were arranged is likely lost to history now. The D&RG record I have shows it looping out of Sapinero..
If the actual track junction was not right at Sapinero, the wire was likely connected in the Sapinero switchboard, and since it was a "loop" there would possibly have been some pole brackets carrying the two wires of the loop from the Depot at Sapinero to where the branch line actually took off away from the main line (Lake Jct).
Running a wire up a branch like this as a loop meant that there were two wires on the branch line to take the circuit to the far end of the branch, and bring it back. There would be no earth connection at the end of the branch. Usually the junction point switchboard could cut the loop out of the circuit if it went in trouble.
This was a very common practice if the loop wasn't too long because it avoided having to have a set of repeaters at the junction point. There were other places like this such as the loop
to Pagosa Springs from Gato (old Pagosa Jct), .and the loops of WU wire 118 and RR No. 1 to Westcliffe (WC) out of Texas Creek, etc.
Ed